Coating applicator and method



April 2, 1957 D. s. WILLIAMSON ETAL comma APPLICATOR AND METHOD 2 Sheets-Sheet 1 Filed Sept. 30, 1954 MIIII I P D. G. WILLIAMSON IETAL 2,787,242

COATING APPLICATOR AND moo Filed Sept. 30, 1954 2 Sheets-Sheet 2 Eran/5T5 Ema/0 G. -Wl/l/k11225012 Melvin W. 51701/61 HZ/mar A. Andrasezz 73422270120 H. Afldresezz United States Patent COATING APPLICATOR AND METHOD Donald G. Williamson, Skokie, Melvin W. Snover, Winnetka, and Hilmar A. Andresen, and Raymond H. Andresen, Barrington, 111., assignors to Williamson Adhesives, Inc., Skokie, Ill., a corporation of Illinois Application September 30, 1954, Serial No. 459,272

3 Claims. (Cl. 118-126) This invention relates to an applicator for and a method of applying a liquid to flexible strip material. The applicator of our invention can be used for applying coatings of various types, including decorative, protective and adhesive coatings, or the liquid to be applied may be an activating liquid for remoistening or solvent activating an already coated flexible strip.

The applicator of our invention includes means defining a reservoir for the liquid to be applied and an applicating unit or sub-assembly. The applicating unit or sub-assembly comprises a non-rotatable member providing a stationary arcuate surface normally extending into the reservoir, and a doctor blade pivotally mounted on said non-rotatable member for movement toward and away from the arcuate surface. The doctor blade has a curved or rounded strip-engaging end portion or foot which is constantly and resiliently biased or urged toward the surface of the stationary arcuate surface on the side thereof that the flexible strip material emerges from the reservoir. Guiding means are provided for directing the flexible strip into contact with the stationary or non-rotatable arcuate surface of the sub-assembly. The strip is initially lapped or threaded around the underside of the arcuate surface and between the arcuate surface and the doctor blade, after which the sub-assembly is mounted in the applicator with the arcuate surface partially immersed in the reservoir of liquid. The springurged or resiliently biased doctor'blade serves the purpose of spreading and gauging the coating or film applied to the flexible strip as it is drawn past the doctor blade. One of the various uses of our applicator is in connection with the application to strips of flexible material, such as paper, cloth, and the like, of a pressure-sensitive adhesive composition. Our device has proved to be very satisfactory for the making, right on the job, of pressuresensitive tape, so that it can be made as it is needed and used on the spot, without the necessity of winding the tape into rolls, spooling or packaging the same. The cost saving is considerable.

a It is therefore an important object of our' invention to provide an applicator of novel and improved construction for the application of liquids, either as coatings, films, :or activating solvents, to flexible strip material. It is a further important object of this invention to provide an applicator through which flexible strip mate rial can be manually drawn and the strip automatically treated on one side with the liquid while the other side of the strip remains untreated.

It is a further important object of this invention to provide an applicator for use on-the-job and by means of which flexible strip material drawn therethrough is ice the simplest type of within a body of the treating liquid, and of controlling the amount and distribution of the applied treating liquid as the strip emerges from the reservoir of liquid and while still in contact with the arcuate stationary surface.

Other objects, features and advantages of this invention will be readily apparent from the following detailed description of a preferred embodiment thereof taken in conjunction with the accompanying sheets of drawings, in which:

Figure l is a side elevational view of the coating applicator of the instant invention with parts broken away and parts in section;

Figure 2 is an end elevational view of the applicating unit or sub-assembly;

Figure 3 is an exploded view illustrating the preferred means employed in mounting the doctor blade on the stationary arcuate surface, and;

Figure 4 is a view illustrating the guide means for guiding the strip material into accurate engagement with the stationary arcuate surface.

The applicator of our invention, which is generally indicated by the reference numeral 10, comprises a reservoir for a liquid and an applicating unit or sub-assembly. The reservoir 11 consists of a generally rectangular vessel or tank having a bottom member 12 and parallel, opposed end and side walls 13 and 14, respectively. If desired, a suitable cover member may also be employed on the reservoir 11. A cover, however, is not necessary for the proper functioning of the applicator and is optional, depending upon the environment in which the applicator is to be used. The reservoir 11 is supported by suitable supporting means such as L-shaped legs 15 having laterally extending, L-shaped brace arms 16 formed integrally therewith. l

A suitable liquid L, with which the flexible strip material is to be coated, is retained in the reservoir 1I;-at a predetermined, substantially constant level as at 17.

The liquid L is fed to the reservoir II from an auxiliary reservoir 18 by means of a cylindrical filling tube 19. As shown in Figure 1, the auxiliary reservoir 18- is preferably located directly above and to one end of the reservoir 11. The auxiliary reservoir 18 may be ofsubstantially any suitable size and shape, and may be mounted in any desired manner. Thecylindrical filling tube 19, which delivers the. liquid L to the reservoirll, also acts in a well-known manner in maintaining a substantially constant level of the liquid L in the reservoir 11. That is, the lower end 20 of the filling tube 19 deblade 25.

The plate 23 has a centrally positioned keyhole slot 26 formed therein. The plate 23 is detachably mounted to the depending support plate 22 by means of a suitable bolt, stud or the like 2'7, having a cylindrical, knurled pressure-exerting nut 28 threadedly engaged on the bolt.

The top end portionuoftheplate 23,:is bent putwfi ldly -on-the arcuate surface '24.

predetermined position :is such :that when :the 'sub assembly 21 is mounted on the depending support plate 22 the'roll -24 will be-subrnergedinme liquid L to just the proper-depth to assure :a proper coating of-the strip materialemployed.

The stationary arcuate surface 24 preferably comprises a hollow cylinder or :roll. If desired, however, the cylinde'r 24 may The solid, 'Ebut for reasons of economy and weight, it is preferably "hollow. The cylinder roll or stationary -arcuate :surface 24 is secured to the plate 23 --by Welding'or the like asat 32. By stationary is meant tha'tithe roll, or arcuate surface 24 is non-rotatable, as -'distinguished from IOllSsOX other rotatable arcuate surfaces which have been commonly used heretofore in coating applicators. This provision of the stationary or non-rotatable roll -such as 24, .as opposed to :rotatable rolls, is not merely arbitrary,'but rather performs a unique and novel function, as will be more clearly brought out as the disclosure progresses.

Means are provided for mounting the doctor blade 25 In the embodiment shown in Figure 3, 'such'means comprise a cantilever structure including the stationary roll 24, a lateral support member 33 and a doctor blade supporting pin 43. The support imember 33, which is preferably cast from a suitable metal, includes a generally tapered'or angular body porti'on'vd, a'laterally projecting circular roll-engaging portion 35 on one end thereof, a boss I36 on'the other end and a longitudinally extending tapered reinforcing rib 37 formed integrally with the body portion 34.

The'circular roll-engaging portion 35 is of 'a'diameter substantially equal to or slightly smaller than the inner "diameter of the hollow roll 24.

The'support member 33 'is'integrally mounted on the-roll 24 by sweating or brazing the roll 24'onto the circularroll-engaging por- =tion 35 which is inserted into the-roll 24.

A closure plug 38 is provided 'for sealing the end of the roll 24 opposite the end on which the support member 33 -is mounted. The closure plug 38 "comprises a flat circular portion 39 and Jan annular'flangexportion 40 formed integrally therewith. The closure plug 38 :may be cast or may lie-stamped froma suitable m'etal.

The' outer diameter of the "plug 38 at thefiange 40 is substantially equal to or slightly smaller than theinner diameter of the hollow roll 24. The plug 38'is mounted in'the roll24 by brazing or sweating.

The boss 36 of the .support'member 33 has abore-41 formed therein-for receiving the steppedend 42-of a doctor blade supporting pin'43. Aligned'apertures 44,

44 are formed on the top'and bottom "surfaces of the boss 36 for alignment with a .bore 45 formed in the stepped end 42 of thesupportingpin'43. A locking pin ddengages the aligned-apertures 44, 44 and the bore45 and firmly holds the support pin 43 against axial and radial-movement. V

The doctor blade 25 comprises a substantially rectang-ular plate having a width justslightlyless thanthe length of the roll-24. It will be realizedfrorn the description of the function of the doctonblade 25, howv as ill b more-apparent-as explalned hereinafter,

that the width of the doctor blade 25 may be varied depending upon the width of the flexible strip being coated. The doctor blade 25 is pivotally mounted on 'the pin 43 "by-means 'oflaterally extending .collars 47 forined.integrally'withitheidoctor-bladefl25. The collars 'f have sernicircular'or. arcuatecut'outportions 48which zasivaeny engage' thesupportpin .43.

s edge upwardly at "the "dependingsupportplate22.

The lower end of the doctor blade 25 is preferably .bent in .a pounded or .curved fashion to form .a ,stripengaging convex portion or foot 49. The function of this curved strip-engaging end portion 49 will be more clearly dealt with in describing the operation of the coating applicator.

This curved strip-engaging end portion 49 is constantly and resiliently biased or urged toward the roll 24 by a spring loaded pressure. This spring loaded pressure is exerted by a clip-type spring 56 which is spiral-1y wound around a threaded shaft 5'1=and: is connected to the sides of the doctor blade 25 by means of hooks formed on the ends of the spring 50, as at 52 andholds the-doctor blade 25 on thesupport; pin 43.

The threaded .shaft51, provides supporting means for an adjustmentmember for regulating thepressureexerted by the doctor .blade toward the'roll 24. This adjustment member, indicated generally at 53, comprise a fumecomically-shaped adjustment nut '54 and a lock nut 55. Both nuts 54 and iSS-are'threadedly engaged on the shaft 51 with the lock nut 55 being positioned beyond the adjustment nut 54. The lock nut 55 can be turned down tightly against:the adjustment nut 54 to lock said adjustmentvnut 54 securel-ydnrplace. Both nuts areknurledrto .provide good fingenengaging-friction when beingturned.v

The shaft 51, is 'welded, braised, or otherwise suitably mounted in aibore formed in the pin 43as at 56.

As seen best in 'Figure 1, the curved strip-engaging end portion or foot 49 of the doctor blade 25 -is-normally constantly and resiliently biased or urged in aclockwise direction by the spring 50 toward the roll '24. In

this manner, -theqstrip-engaging portion 49-is effectively held against av strip of flexible material M interposed betweenthe roll 24 and the doctor blade 25. The amount of this --spring-loaded pressure exerted by the-strip-engag- 'ing portion 49 may 'be'regulated by the adjustment nut 54. As seen in Figures -1 and 2, the upper cdgepor- 'tionof the-doctor-blade 25 is bent outwardly to form a laterally extending flange '57. An arcuate cut-out portion 57a ofthevfree edgeportion of the'flange:57;abuts against the outer;peripheral surface of the downwardly in opposition to the clockwise pressure exerted bylthe spring 50. For, as the adjustment nut 54 is advanced downwardly on the shaft 51, it exerts or produces a canuning effect on the flange 57. That, is, asthezadjustment nut 54 is advanced downwardly, the flange .por-

tion .57 of the. doctor;bl-ade 25 rides upwardly andioutwardlyzin a counter-clockwise directionon the :tapered surface of the nut.'54. Thus, :by properly turning the ad ustment nutz 54 upwardly or downwardly Qntheshaft 51, one may.carefully-and accurately regulate and adjust the pressure exerted by the curved-strip-engagingvportion 49.toward the; roll 24 and against the strip of flexible ma- .terial-M.

.ln initially operatingthe'coatingapplicator of the in- =sta nt.-1nvention,the following procedure is employed:

First, the..nut 28 is threadedcif .thezbolt 27tand the applicating sub-assembly 21 r is detached :"from the pilot pin 30 and the bolt127 and removed from the applicator A strip of the desired flexible material M, which-is obtained :from a suitable source (not shown), such as a rollaof'flexiblefistripmaterial retained in elevated positioniab'ovethe applicator, is then looped under the bottom The adjustment nut 54 is then threaded down to force the curved foot portion 49 of the doctor blade 25 away from the roll 24, to form a gap between the doctor blade and roll. The loop of flexible material M is then passed or slipped over the roll 24 into said gap from the open end of the sub-assembly 21 shown generally at O. The strip M is thus looped or lapped around the roll 24 and passes between the doctor blade 25 and the roll 24.

The restraining force of the adjustment nut 54 is then released and the doctor blade is adjusted by means of the nut 54 so that the curved strip-engaging end portion 49 of the doctor blade 25 is maintained at a predetermined spaced distance from the roll 24. In this manner the liquid L is spread evenly on the strip M and a uniform thickness of the layer of liquid L is maintained along the entire strip M thus coated. As is readily seen, the thickness of the liquid L is controlled by the space between the roll 24 and the curved end portion 49 of the doctor blade 25. This distance, in turn, is controlled and adjusted by the nut 54.

Next the sub-assembly 21 is mounted on the depending support plate by aligning the pilot pin 30 with the aperture 31 and the bolt 27 with the key hole slot 26. The sub-assembly 21 is then held rigidly in place by threadedly engaging the retaining nut 28 on the bolt 27.

In this mounted position the strip M is held snugly against the roll 24. The roll 24, in turn, is submerged into liquid L just to the proper depth to ensure a complete coating of the strip M without unduly coating the closed ends of the roll 24.

Means are provided for guiding the movement of the strip M into engagement with and around the roll 24. As shown best in Figures 1 and 4, such means include parallel ears or tabs 59 having a bar or pin 60 mounted therebetween. Guide collars 61 in the. form of movable discs are slidably mounted on the bar 60. Each of the guide collars 61 is provided with a set screw 62 allowing said collars to be coaxially adjusted and set to accommodate the guidance of flexible strips of varying widths.

' In this manner the strip is always properly aligned with the arcuate surface of .roll 24; preventing twisting, tearing or misalignment which might otherwise occur during the coating of the strip M.

The depth to which the roll 24, having the lapped therearound, is immersed into the liquid L in reservoir 11 is not critical, provided that there is sufficient immersion to assure a complete and continuous coating of the strip M with the liquid L as the strip M is drawn over the roll 24 through the liquid L and past the doctor blade 25. It will also be appreciated that the depth of immersion can vary with the viscosity and nature of the liquid L being employed and the properties of the strip M.

The depth to which the roll 24 can be immersed may be controlled by adjusting the position of the pilot pin and/or the level of the liquid L in the reservoir. The level 17 of the liquid L of course, can be easily regulated by raising or lowering the end 20 of the delivery pipe 3'19.

The strip M is preferably manually drawn through the applicator. It will be realized, however, that if desired, the strip M may be drawn through the applicator by mechanical means, such as a mechanically driven reel or the like. Also, if desired, or if required by the nature of the liquid L with which the strip M is coated, the strip M after being drawn through the applicator and coated with the liquid L may be led through suitable drying means to dry or otherwise process the coating of the liquid L onthe strip M. The requirements for drying or the like, however, will vary depending uponthe particular job and the nature of the liquid.

In the instant invention, the stationary arcuate surface of the roll 24 efliciently effects the coating of only one side of the strip M with the liquid L. The tension exerted on the strip M as it is drawn around the roll 24 frictional sliding engagement between the surface of the strip M V strip M which is in contact with the surface of the stationary roll 24 and the hydraulic pressure of the liquid L exerted upwardly against the strip M. This engagement and hydraulic pressure provides a sufiiciently tight seal to prevent the influx of the liquid L between the strip M and the roll 24. Accordingly, only the obverse or oppo site side of the strip M, which is not in contact with the roll 24, comes into contact with and is coated by the liquid L.

As noted above, the prevention of influx of the liquid L between the strip M and the roll 24 is primarily a result of the tension exerted upon the strip M as it is drawn through the applicator. This tension, in turn, is produced by the stationary character of the roll 24, and is largely a product of the friction produced by the: sliding engagement of the strip M over the stationary arcuate surface and the hydraulic pressure of the liquid L exerted upwardly against the strip. Accordingly, if the friction created by the sliding engagement of the strip M over the roll 24 were reduced or eliminated, the hugging pressure of the strip M against the arcuate surface would, likewise, be diminished. By the same token, if the tension on the strip M were reduced, the prevention of the influx of the liquid L between the strip M and the roll 24 would be correspondingly difficult, if not impossible, to prevent.

Heretofore, arcuate surfaces or rolls and the like employed in coating applicator mechanisms similar to the instant invention have always been rotatable, rather than stationary surfaces. in all such prior applicator structures, it was necessary to provide supplementary or additional tensioning means to prevent the influx of the coating liquid between the strip being coated and the rotatable or otherwise non-stationary arcuate surfaces over which the strip was drawn. These supplementary tensioning means were-not only items of added expense, but also complicated the operation of the applicator and increased its size and weight. Also, in many instances, the supplementary tensioning means were somewhat difficult to control.

In the applicator of the instant invention, however, the novel function of the stationary roll 24 in preventing the influx of coating liquid L between the strip M and the roll minimizes the need for supplementary tensioning means, for the tension exerted on the strip M as it is fed off a supply roll and around the stationary roll 24 supplies a sufficient amount of tension. This results in'a simpler construction which decreases initial cost, subsequent main tenance and upkeep and makes for a lighter weight structure which increases the portability of the applicator.

The doctor blade 25 having the curved strip-engaging foot or end portion 49 formed thereon evenly spreads the liquid L as a uniform layer on the strip M and accurately gauges the thickness of said layer on said strip. By means of the novel adjustment nut 54 acting against the resiliently biased doctor blade 25 it is possible accurately to gauge the thickness of the layer of the liquid L on the strip M regardless of the viscosity of the coating liquid employed. The rounded structure of the curved strip-engaging end portion 49 leads and forces the liquid L into the nip between the strip-engaging; foot 49 and the roll 24 and accurately determines the thickness of the layer of the liquid L. In the doctor blades employed heretofore in coating applicators similar to that of the instant invention, this desirable spreading and gauging by the doctor blade were not always possible, for previous doctor blades did not have curved or rounded strip-engaging portions. Rather, such doctor blades had straight, fiat, or at the best, blunt strip-engaging end portions. Such straight strip-engaging edges tend to scrape the coating liquid oil the strip. Accordingly, doctor blades employed heretofore did not always accurately gauge the thickness of the layer, and indeed, in some instances, would occasionally effect a scraping action which would remove the liquid from the strip, rather, than aiding the coating'of the strip with the liquid.

.moving the spring '50. This'facilitates easy cleaning of the structure.

Another feature lies in the fact that the-entire applicating sub-assembly 21 may be removedfrom'the applicator while'the strip M is being lapped around the roll 24. As compared to standard applicators, wherein the strip must'be threaded throughthe adhesive during loading, the strip M in, the presentstructure does not touch the adhesive while the apparatus is being set up. This cleaner and simplermethod oflapping the strip around the roll while the sub-assembly 21 is dismounted results in less tape or strip material being wasted by the inadvertent coating of the tape on both sides during the loading procedure.

The applicator of the instant invention is capable of operating with liquids of various types and characteristics. A few examples of the various categories into which the liquids, or-at least the flowable treating materials may fall are: coatings of a decorative, protective, or adhesive character; and surface activating or deactivating applications, which'may include the remoistening'or solvent activating of films or coatings already present on the-flexible strip, or for deactivating other types of surfaces. An ordinary gummed strip may, for instance, be drawn through our applicator for moistcning with water,'which would then be the liquid L within the reservoir 11.

Since our applicator'may find its greatest use in connectionwith the application of adhesive coatings-to flexible strip material, we shall briefly mention some of the various types of liquid ahesives whi-chmay be used. These would include water soluble adhesives of the dextrin, starchy, casein, animal glue or soluble gum'or resin type; colloidal solutions of animal glue, starch, or the like; colloidal dispersions and emulsions, with either Water or an organic -Example I Materials: Percent by weight Dextrin 30.0 Borax 5.0 Sodium hydroxide 0.6 Preservative 0.2 Water 64.2

Example II Materials: Percent by weight Casein 16.0 26 B. ammonia 10.0 Preservative 0.5 Water 73.5

Example HI Materials: :Percent by weight Gum arabic 40.0 Prescrvative 0.2 Water 59.8

Example IV Materials: Percent by weight Animal glue 40.0 Liquefler, such as calcium chloride 10.0 Preservative 0.5 Water ss149.5

Exainple V Materials: Percent by weight Rubber 1 5.0 Plasticizer =15-.0

Naphtha 70.0

Among.theself-supporting flexiblematerials that may :be used in strip,rribbo n, tape, or other more or less continuous web form may be mentionedpaper, cloth, plastic, metal, and woodveneer. Themetal, of course, would be in the form of thin sheets,'f oil, or the like, and would include steel, aluminum and lead.

One of the advantages of our applicator and dispenser is that of being conveniently adapted for use with intermittently run equipment, such as for example in box making equipment, where the flexible strip material may be treated, coated or the like only as and when needed. It is not necessary, therefore, to use ready-made tape that must be moistened before being applied, or expensive ready -made pressure sensitive tape. The latter is relatively more expensive because of all of the added steps of spooling and packaging, andinsomeinstances supplying special release surfaces to facilitate unwinding without ole-lamination.

It will be apparent to those skilled in .the art that we have now provided anew and improved applicator-for ap plying liquid to a flexible strip material. It will also be appreciated that the applicator of this invention can be used for applying coatings of various types, including decorative, protective, and adhesive coatings, as well as for the application of activating liquidsfor remoistening or solvent activating analready coated flexible strip.

it will, of course, be understood that various details of the invention may be varied through a wide range Without departing from the principles of this invention, and it is, therefore, not the. purpose to limit the patent granted hereon otherwise than necessitatedby the scope of the appended claims.

We claim as our invention:

1. An applicator for applying a liquid to a flexible backing strip, which comprises a reservoir for said liquid, a sub-assembly including a non-rotatable member providing an arcuate surface normally extending into said reservoir and a doctor blade supported from said member and pivotally mounted for movement toward andaway from said arcuate surface, said doctor blade having a curved strip-engaging end portion thereon, .means constantly and resiliently biasing said end portion toward said arcuate surface for evenly spreading vsaid liquid on said strip and for gauging the thickness of v said layer on said strip, and a threaded adjustment member for adjusting the pressure exerted by. said doctor blade toward said arcuate surface.

2. An applicator for applying a liquid to one .side only of a flexible backing strip which comprises a reservoir for said liquid, a detachable support plate having a non-rotatable member providing 1 an arcuate surface mounted integrally thereon normally extending into said reservoir and a doctor blade supported from saidmember and pivotally mounted for movement towardand away from said arcuate surface, said doctor blade having a curved strip-engaging end portion thereon, means constantly and resilientlybiasing said endportion toward said arcuate surface for evenly spreading said liquid as a layer on said strip and'for gauging the thickness of said layer on said strip, and threaded adjustment means for adjusting the pressure exerted by-saiddootor blade toward said arcuate'surfiace.

3. An applicator for applying a liquid to one side only of a flexible backing strip which comprises ja reservoir for said liquid, a detachable sub-assemblypincluding a supportplate having a non-rotatablemember providing an arcuate surface mounted integrally'thereon normally extendinginto said reservoiranda doctor blade supported from said member and pivotally moun-ted' for movement toward and away from said arcuate surface, said doctor spam-1a blade having a curved strip-engaging end portion thereon, means constantly and resiliently biasing said end portion toward said arcuate surface for evenly spreading said liquid as a layer on said strip and for gauging the thickness of said layer on said strip, means for adjusting the pressure exerted by said doctor blade toward said arcuate surface, and guide means above and adjacent said arcuate surface for guiding said flexible strip over said arcuate surface through said reservoir and past said doctor blade.

References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS Denmark Dec. 30, 1946 

